The present invention relates generally to lighting systems, and more specifically to compact modular fluorescent light systems constructed to provide power to at least one and preferably a plurality of fluorescent lamps which can be energized individually or in selected combinations.
Fluorescent lamps are well known to be much more efficient in producing light output for any given electrical energy input, compared to incandescent lamps. Thus, a fluorescent lamp will consume far less electrical energy than will an incandescent lamp when each provides the same amount of illumination. The cost of providing light, therefore, is significantly less when fluorescent lamps are used rather than incandescent lamps. The cost savings of using the fluorescent lamps is particularly important in situations requiring the use of many lamps for extended periods of illumination, such as found in industrial plants and hotels and motels. In addition to consuming less electrical energy per unit light output than incandescent lamps, the fluorescent lamps have longer lifespans than the incandescent lamps, thereby reducing the frequency of replacement, consequently reducing labor and material costs over the term of use of the lamps.
The significance of the ecological, as wall as the economic, advantages of fluorescent lamps over incandescent lamps is recognized by electrical power and local government authorities, which often provide tax or other incentives to those who use fluorescent lamps. For example, the Long Island Lighting Company encourages the installation of energy saving technologies though its 1994 Energy Wise Program. That program provides, among other incentives, rebates for installation of fluorescent lighting to replace incandescent lighting. Typical rebates at the present time are $0.35 per incandescent lamp and $10-$40 per fluorescent lighting fixtures which permanently replace incandescent fixtures. Such rebates can be very important economic incentives which result in ecological benefits as well, particularly in high volume usage of lighting, as in hotels and in industrial installations.
It is important to understand, however, that such rebates normally are not available for light fixtures which enable the use of fluorescent lamps but which also enable the replacement of fluorescent lamps by incandescent lamps. The power companies typically do not approve rebates until they have inspected the applying facility to confirm that the fluorescent fittings are permanent.
Recognition of the advantages of fluorescent lighting is well established. However, the lighting industry has been confronted with some problems which limit the uses of fluorescent lighting. For example, in new installations it is easy to plan for fluorescent lighting fixtures as part of the overall construction, but in established sites, the need to retrofit for fluorescent lighting is not as simple. Where it has not been economically or physically practicable to remove existing incandescent fixtures and install new fluorescent fixtures, the advantages of the latter might never be realized.
Efforts have been made to find ways to use existing lighting fixtures designed for using incandescent lamps and adapt them to the use of fluorescent lamps. Such efforts to date have resulted in devices such as that disclosed in U.S. Pat. No. 4,348,612 to Morton, which is a self-contained fluorescent light adapter which includes a fluorescent lamp, a lamp socket, a ballast transformer, capacitors, a lamp cover and a screw base for attaching to incandescent light fixtures. Another attempt to adapt fluorescent lamps for use in incandescent light fixtures is shown by U.S. Pat. No. 5,202,607 to Broyer et al. That device provides two fluorescent lamps combined into a single self-contained adapter whose case also includes lamp sockets, two ballast transformers and a base that screws into typical incandescent lighting fixtures to make electrical connection to power supplies. Those adapters, because they are assembled as single units, are designed to be installed and removed easily from incandescent fixtures with no more effort or knowledge than that required to install or remove incandescent lamps. And they are designed to enable anyone to insert them into incandescent light fixtures without the need for additional parts or equipment, such as ballast transformers, as they are contained in a single adapter case.
Although such adapters have made some limited progress in expanding the use of fluorescent lighting in residential use, in practice they have some very significant disadvantages that make them undesirable, especially for use in hotel, motel, commercial and industrial applications. For example, the adapters are expensive to make and expensive to replace, as they include the fluorescent lamps and ballast transformers and related structures as a single, self-contained unit. Replacing such a comprehensive lighting unit is many times more expensive than replacing a fluorescent or incandescent lamp. Thus, even if the high volume user is economically able to purchase the adapters initially, the replacement costs are far higher than the replacement costs for incandescent lamps.
One of the most disadvantageous characteristics of such adapters is the fact (originally asserted to be an advantage) that they are specifically designed to be easily installable and replaceable. While this might be advantageous to the residential user who can control access to the expensive adapters, hotels and other high volume lighting users consider it to be a critical disadvantage considered in their decisions not to use them. This is because the ease with which the adapters are removed, and the fact that the adapters are exposed to very large numbers of people, such as those renting hotel rooms, make the adapters susceptible to easy theft. The advantages of fluorescent lighting is so well known today, that people are easily tempted to remove the adapters from hotels and the like, especially as it is clear that the adapters can be used without any alteration in existing incandescent light fixtures and with no knowledge in addition to that needed to install an incandescent lamp.
The result has been so disastrous for hotels and other high volume users of lighting systems that the initial eagerness to install the adapters has been replaced by a frustration with the theft problem and its resulting high costs. Thus, high volume lighting users have been forced either to continue incandescent use or absorb the exorbitant and unacceptable costs of purchasing replacement adapters long before the end of the useful life of the adapters And the ready replacement of such adapters by incandescent lamps is an attractive response to theft or breakage. The advantages hoped for fluorescent installations using the adapters such as those disclosed by Morton or by Broyer et al. thus are actually unavailable, especially to such high volume lighting users.
One of the clearest indicators of the disadvantages of self-contained fluorescent lighting adapters is the fact that such adapters, like those of Morton and Broyer et al., do not qualify for rebates offered for fluorescent installations by some power companies, for example, Long Island Lighting Company. The reason for this is that the power company investigates the new or retrofitted installations for fluorescent lighting systems and grants such rebates if it is determined that the fluorescent systems are permanently installed. By contrast, the ease of removal and insertion of the self-contained fluorescent adapters of Morton and Broyer et al., asserted to be an advantage, also makes such adapters easily replaceable by incandescent lamps. Thus, the power companies cannot verify that installation of such fluorescent lighting systems is permanent, and therefore rebates are denied.
Another disadvantage of adapters such as those described in Morton or Broyer et al. is that because they are designed to be self-contained units complete with the required ballast transformers, they are bulky and have been found not to fit some commonly used lighting fixtures. Even if such adapters can be used, it is often necessary also to replace standard size lamp shades with larger lamp shades, thereby again reducing the incentive of purchasers and increasing their costs if they do purchase the adapters by virtue of the need to purchase different lamp shades as well.
Not only do the adapters sometimes not fit within standard sized shade supporting harps of fixtures, but they are also quite heavy because they contain one or more ballast transformers. As another disadvantageous result, if such adapters are placed on "armed" fixtures, such as swing arm fixtures, their excessive weight tends to tip the lamps over. This not only risks breakage of the adapters so as to increase replacement expenses, but also creates enhanced risk of fires and electrical shock resulting from the fixtures tipping over and breaking. And such adapters cannot practically be used in lighting fixtures of the counterbalanced arm type because the weight of the ballast transformers in the adapters would require a very heavy and expensive counterweight at the opposite end of the counterbalanced arm of the fixture.
Yet another disadvantage of self-contained adapters such as those described in Morton and in Broyer et al. is that because they are designed to be used in existing incandescent fixtures, the adapter case must be made dimensionally as small as possible. Because the ballast transformers are contained in the case as a single unit with the sockets and lamps, they are forced closely together. But doing so results in excessive heat production by the adjacent ballast transformers, with resulting increase of heat transfer from the transformers to other parts of the fluorescent lighting system, notably the light sockets and lamps.
Even when thermal barrier walls are provided to separate ballast transformers, those walls decrease the circulation of air in the case, even if ventilation openings are provided, which is directly contradictory to the intended benefit of such thermal barrier walls. This increases the risk of fire and also increases the risk that the ballast transformers will fail or be significantly reduced in terms of useful life. This, in turn, increases the overall cost to the user of adapter replacement, especially for high volume users such as hotels and industrial plants.
One of the goals of adapters, such at that disclosed in Broyer et at., is to provide two or three stages of illumination by selectively switching the power supply to different fluorescent lamps or to different combinations of lamps, thereby providing lighting similar to the well known three-way incandescent bulb. As desirable as that is in principle, the disadvantages of such adapters is compounded by efforts to provide such multiple stage lighting because the number of ballast transformers required increases with the increase in the number of stages of lighting for which the adapter is designed. As the adapters are self-contained with lamps, sockets, ballast transformers and screw-in bases, the three-way capability is offset by the increase in physical bulk, weight and required size of the adapter cases. The physical limitations on such self-contained adapters discourage the making of fluorescent lighting systems which have more than three levels of illumination. This is especially true in light fixtures having swing arms or cantilevered construction.